Control for air conditioning systems



Feb. 21, 1939. R, P. DEWEY CONTROL FOR AIR CONDITIONING SYSTEMS 2 Sheets-Sheet Filed March 27, 1936.

INVENTOR v Ritchie P. .Deweg BY fw ATTORNEYS Feb. 21, 1939. R. P. DEWEY CONTROL FOR AIR CONDITIONING SYSTEMS 2 Sheets-Sheet 2 Filed March 27, 1936 To LINE 4O modifications and alternative constructions, I Shaft 2| Which carries a Crank 22 Connected y Patented Feb. 21, 1939 t UNITED: STATES PATENT OFFICE CONTROL FOR- AIR CONDITIONING SYSTEMS Ritchie P. Dewey, Rockford, 111., assignor, by

mesne assignments, to Barber-Colman Company, Rockford, 11]., a corporationof Illinois Application March 27, 1936, Serial No. 71,233

13 Claims. (01. 236-1) This invention relates generally to air condiin the room at points remote from each other. tioning systems and more particularly to those The unit ventilator comprises generally a casof the so-called blast type in which the tempera- 'ing 9 providing an air duct Illcommuni'cating at ture of the air discharged into the space to be one end with a fresh air inlet II and a duct l2 5 conditioned may be cooler or warmer than that into which return or recirculated air from the 5 in the space. room may enter through an opening l3 disposed The primary object of the invention is to proadjacent the floor. A power driven blower l4 vide an air conditioning system of the above within the duct Ill operates to draw air through character having a plurality of temperature the inlets and discharge the same into the room changing units and novel means for interconthrough an opening I5. 10 trolling the operation of such units to prevent The proportion of fresh air in the mixture is operation thereof at cross-purposes whereby to determined by the positions of dampers I6 and obtain optimum economy in operation and ac- I! located in the fresh and return air ducts and curacy of temperature control. connected by a link l8 in a manner such that the A more detailed object is to provide a novel fresh air damper iS fully opened When the return 15 thermostatic control forgoverning the operation r d mp s Closed a the fresh a da pe is of a plurality of unit ventilating systems whereompl tely clo d wh n the re rn ir d mp is by the heater of either system will be mainfully op y Shifting the link back and tained inactive so long as the fresh air damper forth, the proportion of fresh air in the 30 of the other system is opened beyond a predeterture m y be v rie pro i ly. Thus, when mined minimum position, the temperature of the fresh air is below that Another object is t provide a novel system of theroom, the temperature of the recirculated for thermostatically controlling the movements may he eooled to the desired degree y of the fresh air damper and the heat controller lusting the position of the fresh damper to in a heating system of t m t; type correspond to the cooling requirements of the 25 Other objects and advantages of the invention will become apparent from the following detailed In the present instance, the fresh air inlet is description taken in connection with the accomfully closed- When the damper Cooling egupanying drawings, in which lator is in its minimum operating position. It

Figure 1 is a plan sectional view of a room willhe e e v however, theta m OD- equipped with an air conditioning system emeTet1ng DoS1t10I 1 maybe ted n w loh the bodying the novel features of the present invenfresh elr Inlet 1s Partially open so t edet termined minimum amount of fresh air will al- Fig. 2' is a vertical sectional view of one of the W be pp d t the m ri p ra ion unit ventilators. of the system. 35

Fig. 3 is a sche ti i d wiring diagram Preferably the fresh and return air dampers of the air conditioning units and t mechanism of the unit ventilator 5 are actuated by a power for controlling the operation thereof. Operator Comprising an electric motor I9 con- While the invention is susceptible of various neeted through Speed reduction ar n 0 to a have shown in the drawings and will herein dea rod 23 t0 the link 80 that the a p 40 scribe in detail the preferred embodiment, but will be moved from the fully open position shown it is to be understood that I do not thereby intofully closed position in a half revolution of tend to limit the invention to the specific form the shaft 2| in a clockwise direction. The motor disclosed, but intend to cover all modifications shown is of the reversible shaded pole induction 45 and alternative constructions falling within the ype h vi a a Winding 24 constantly enerspirit and scope of the invention as expressed in gized from an alternating current source 25 and the appended claims. having two sets 26 and 21 of shading coils ar- In the drawings, the invention is shown for ranged on the stator poles and adapted to be purposes of illustration embodied in a system for short-circuited selectively to cause the rotor 28 50 conditioning the air within a room 4 and comto turn in one direction or the other. The arprising two so-called unit ventilators 5 and 5 arrangement is such that the rotor will turn clockranged to discharge currents of conditioned air wise and the fresh air damper 16 will be closed into different parts of the room and respectively progressively when the coils 21 are short-cirv controlled by thermostats I and I located withcuited. Reverse rotation and opening of the 55 fresh air damper occur when the coils 26 are short-circuited.

The unit ventilator 5 is equipped with a heating unit for supplying heat to the air delivered to the room. Herein this unit comprises a heater in the form of a steam coil 29 herein interposed in the return air duct l2. The capacity of the heater may be varied progressively by modulating the opening of a valve 30 in the supply line 3| leading to the heater. This valve has a movable disk 32 which is actuated by an independent elec tric operator similar in construction to the damper operator, being moved toward and away from closed position by a cam 33 acting on a follower 34 and fast on a shaft 35 operated by a reversing motor 36 having shading coils 31' and 38. When the coils 31 are short-circuited, the valve disk is moved toward open position, closing of the valve occurring while the coils 38 are active.

The thermostat is of standard construction comprising a sensitive element 39 carrying a tongue having thereon the common contact of two switches 40 and 4| which are closed respectively when the room temperature is above and below the control point for which the thermostat is set. The thermostat T is similarly constructed.

The unit ventilator 5' is of the same construction as the unit 5, and the dampers and valve thereof are actuated by individual electric operators in the same way. The parts of the unit 5 are correspondingly numbered and identified by the exponent In air conditioning systems of the above general character having independentlyoperable heating and cooling devices controlled by the same or separate thermostatic means, conditions may prevail under which the devices tend to operate at cross-purposes. For example, due to drafts in the room, one unit may be operating on its cooling cycle while the thermostat controlling the other unit is calling for 'heat. To overcome this difliculty and provide for optimum economy in operation and accuracy of control ofthe room temperature, the presentinvention contemplates a novel system of intercontrolling the individual operators of the same and of the different air conditioning units in a manner such thatfneither heater can be rendered active under the control of its thermostat until the cooling device, that is, the fresh air damper I 5 of the associated unit and also the cooling device of the other unit are in minimum operating positions.

In effecting such intercontrol, the electric motors l9 and 36 are placed in operative control of the thermostat I one at a time according to the positions of the valve and dampers. For this purpose, the short-circuit of the shading coils 21 extends from ground through the coils, a conductor 42, a limit switch 43 which is held closed by a cam 44 when the fesh air dampers |6 are in any other than fully closed position, a conductor 45, the switch 4| of the thermostat and to ground. The circuit for the coils 26 extends from ground through the coils, a. conductor 46, a limit switch 41 which is held closed by a cam 48 except when thedampers |6 are fully opened, a conductor 49, a switch 5!) controlled by a cam 5|, a conductor 52, a switch 53 controlled by a cam 54, a conductor 55, the thermostat switch 40 to ground. The cams 5| and 54 are similarly shaped and adapted to hold their switches closed only when the operating shafts 35 and 35 are in valve-closing positions. As a result of this circuit arrangement,

complete closure of the both valves 30 and 30' is a condition precedent to opening of the fresh air dampers l5 under the control of the thermostat switch 40.

When the fresh air dampers I6 are closed to their minimum operating position, the control of the thermostat 'l is transferred to the motor 36 so that the position of the valve 30 and therefore the capacity of the heater may be adjusted in accordance with the heating requirements in the room. To this end, the circuit for the shading coils 31 extends from ground through the coils, a conductor 51, a limit switch 58 which is closed by a cam 59 except when the valve 30 is fully open, a conductor 60, a switch 6| controlled by a cam 62, a conductor 63, a switch 64 controlled by a cam 65, and a conductor 66 joined to the conductor which leads to the thermostatic switch 4|. The cams 62 and 65 are so shaped that their switches will remain open when the fresh air dampers l6 and I6 are partially or fully open and will be closed only when the dampers are fully closed. As a result, the motor 36 cannot operate and accordingly the steam valve 30 cannot be opened under the control of the thermostat switch 4| until the fresh air dampers of both unit ventilators are closed. The circuit for the shading coils 38 extends from ground through the coils, a conductor 66, a switch 61 held closed by a cam 68 except when the valve 30 is fully closed, the conductor 55 and the switch 40.

The circuits for the motors |9' and 36 of the unit ventilator 5' are similarly controlled by the switches 40' and 4| of the thermostat 1'. Thus the coils 21' are short-circuited through a conductor 42', a limit switch 43', a conductor 45', and the switch 4|. The circuit for the coils 26' is through a conductor 46, the limit switch 41', a conductor 10, a switch ll held closed by a cam l only when the valve 30 is closed, a conductor 12, a switch 13 held closed by a cam 14 when the valve 30' is closed and a conductor 15 leading to the switch 40.

The coils 38' may be short-circuited through a conductor 66', and a limit switch 61' connected to the conductor 15 which leads to the switch 40'. The circuit for the coils 31' is through a conductor 51, a limit switch 58', a conductor 16, a switch 11 held closed by a cam 18 only when the dampers l6 are closed, a conductor 19, a switch 80 held closed by a cam 8| when the dampers l6 are closed, and a conductor 82 connected to the conductor 45' which leads to the switch 4 As a result of the circuit arrangement above described, it will be observed first that the heater 29 of either unit ventilator is maintained inoperative so long as the associated fresh air damper or the fresh air damper of the other unit ventilator is positioned to effect cooling of the room, that is, is partially open. Second, neither of the fresh air dampers can be opened under thermostatic control so long as either of the heaters is active as evidenced by partial opening of either steam valve. In this Way, neither unit ventilator can operate on its heating cycle while the other is conditioned for cooling even though one of the thermostats may be calling for. cooler air while the other is calling for heat.

I claim as my invention:

1. An. air heating system having, in combination, a duct having an outlet communicating with a space to be heated, a fresh air inlet, a second inlet for receiving air to be recirculated from said space, a heater for the air in said duct, a damper controlling the fresh air inlet, a valve controlling the flow of heating medium to said heater, a power operator arranged to impart graduated regulating movements of varying lengths in opposite directions to said damper, an independently operable power operator for modulating the opening of said valve, a thermostat responsive to temperature changes in said space, and means operating automatically in' response to the movements of said damper and valve to place said thermostat in exclusive control of the damper operator when the valve is closed and the damper opened beyond a predetermined minimum position and to place the thermostat in exclusive control of said valve operator when said damper is closed to said minimum position.

2; The combination with two unit ventilators arranged to deliver air to a room to be conditioned of a thermostat in the room acting to vary the proportion of return and fresh air delivered by one of said unit ventilators, a thermostat located within the room at a point remote from said first mentioned thermostat and controlling the heater of the other unit ventilator, and means responsive to the movements of the fresh air damper of said first mentioned unit ventilator to maintain said heater ineffectual irrespective of the condition of said second thermostat so long as the freshair damper of the first unit ventilator is opened beyond a predetermined position.

3. The combination with two unit ventilators arranged to deliver air to a room of independently operable thermostats located at spaced points Within the room and each arranged to control the movements of the fresh air damper and the heat regulating device of one of said unit ventilators, and means operating automatically to maintain the heat regulating device of one unit ventilator inactive independently of its controlling thermostat so long as the fresh air damper of the other unit ventilator is opened beyond a predetermined minimum position.

4. The combination with two unit ventilators arranged to deliver air to a room, of independently operable thermostats located at spaced points within the room and each arranged to control the movements of the fresh air damper and the heat regulating device of one of said unit ventilators, and means operating automatically to maintain the heat regulating device of either unit ventilator inactive independently of its controlling thermostat except when the fresh air dampers of both unit ventilators are closed to predetermined minimum operating positions.

'5. The combination with two unit ventilators arranged to deliver air to a room, of independently operable thermostats located at spaced points within the room and each arranged to modulate the movements of the fresh air damper and the heater of one of said unit ventilators to vary progressively the temperature of the air delivered thereby, and means responsive to changes in the heat-delivering capacity of said heater and operating automatically to maintain the fresh air damper of one unit ventilator in a minimumoperating position independently of the condition of its controlling thermostat so long as the heater of the other unit ventilator is supplying heat.

6. The combination with two unit ventilators arranged to deliver air to a room, of independently operable thermostats located at spaced points within the room and each arranged to control the movements of the fresh air damper and the heaterof one of said unit ventilators, and means operating automatically to maintain the fresh air damper of one unit ventilator in a minimum operating position independently of the condition of its controlling thermostat so long as the heater of either unit ventilator is active and supplying heat.

7. In asystem for conditioning the air within a room, the combination of two unit ventilators each operable selectively to deliver cool or heated air to said room, two thermostats located at spaced points in said room and controlling said unit ventilators, and means intercontrolling the operation of the unit ventilators to prevent one from delivering heated air under the control of its thermostat while the other unit ventilator is delivering cool air.

8. The combination with two unit ventilators arranged to deliver air to a room, of independently operable thermostats located at spaced points within the room and each arranged to control the movements of the fresh air damper and the heat-regulating device of one of said unit ventilators, and means operating automatically to maintain the heat-regulating device of one unit ventilator in non-heating position independently of its controlling thermostat until the fresh air damper of the other unit ventilator has been fully closed.

9. In a system for conditioning the space within a room of the building, the combination of means for delivering a mixture of fresh and recirculated air to said room, a damper controlling the proportion of said fresh air in said mixture, thermostatically controlled means modulating the movements of said damper, a heater for supplying heat to the room, an independently operable thermostat within the room, a power operator controlled by said thermostat and operating to modulate the heating capacity of said heater, and means responsive to the movements of said damper and automatically controlling said operator to maintain the heater inactive independently of said thermostat while said damper is open to a predetermined position and to restore the control of the thermostat when the damper is closed to such position.

10. In a system for conditioning the space within a room of the building, the combination of means for delivering a mixture of fresh and recirculated air to said room, a damper controlling the proportion of said fresh air in said mixture, thermostatically controlled means modulating the movements of said damper, a heater for supplying heat to the air, an independently operable thermostat controlling the operation of said heater, and means operating automatically to withdraw the heater from the control of said thermostat when the damper is open to a predetermined position and to restore the control of the thermostat when the damper is closed to such position.

11. In a system for conditioning the air within a building, the combination with a device movable back and forth to control the cooling of the ture changes of the conditioned air, and means operating independently of said second thermostat and controlling said second operator to maintain said member in non-heating position until the cooling effect controlled by said first mentioned device has been reduced to a predeterments to said devices, thermostatic means controlling said operators to determine the direction and extent of movement of said devices, and means operating independently of said thermostatic means and by movements of said devices to intercontrol said operators and prevent movement of one device away from its predetermined position until the other device has been returned to its predetermined position.

13. In a system for tempering the air within a building, the combination with a device movable back and forth to modulate cooling of the space to be conditioned in accordance with its position relative to a predetermined position, a heat control device movable back and forth to modulate heating of the space in accordance with the position of the device relative to a predetermined position, individual thermostatic actuators for the respective devices each operable in response to temperature changes in said space to control the direction and extent of modulating movement of its associated device, and automatically operating means responsive to movements of one of said devices for intercontrolling the operation of said actuators to maintain the other device in its predetermined position until the former device has been returned to its predetermined position.

'RITCHIE P. DEWEY. 

